6 ms·
240-Gbit/s sub-THz wireless communications using ultra-low phase noise receiver
- kennethrc 3y agoApropos of absolutely nothing, but IIRC a "Star Trek" movie where a screenshot of one of the displays on some ship or another had the Shields Frequency up which allowed the enemy to match it and disable it, and back in the 80s(?) when this came out I remember thinking "237GHz" (or something like that) was an insanely high frequency and doubted it could ever be reached with any degree of stability. Physics: HMB
- moreati 3y agoI thought it might be Generations, but that was 257.4 MHz https://www.youtube.com/watch?v=6A9IZHWz45Q&t=20s https://www.youtube.com/watch?v=6A9IZHWz45Q&t=20s
- kennethrc 3y agoThat's the scene. Says it's from 1994. After that, I'm sure the Owner's Manual that comes with your new Enterprise-class Starship now has a "DO NOT DISPLAY YOUR SHIELD FREQUENCY" in the "Warnings" section
- Cthulhu_ 3y agoI mean I get that series like Star Trek rely on technobabble and suspension of disbelief, but surely an enemy can just... detect the frequency, or rapidly adjust their own like tuning in until it matches?
- mmh0000 3y agoThat would work, but modern starships use a rotating phased tachyon field to prevent that.
- AlexAndScripts 3y agoWith an inversed polarity!
- unaesthetic 3y agoAnd fitted with six hydrocoptic marzlevanes to the ambifacient lunar waneshaft to effectively prevent side fumbling.
- rickydroll 3y agogo home, Scotty, you are drunk!
- mhandley 3y agoFor those who have never had the oportunity to learn of the marvels of the Turbo Encabulator: https://www.youtube.com/watch?v=Ac7G7xOG2Ag https://www.youtube.com/watch?v=Ac7G7xOG2Ag
- calamari4065 3y agoYes. It happens every third episode.
- mmh0000 3y agoTo be fair, we don't know if Starfleet ever figured out how the Klingons bypassed the shield. Nor do we know if they ever discovered someone installed a rootkit on Geordie's visor. Also, given Starfleet's continued examples of not learning their lessons from previous encounters, I suspect all ships still display the shield frequency in big, bold font. Possibly even visible from the viewscreen of the bridge on one of the rear consoles.
- cornholio 3y agoThat's the shield modulation frequency though, so the actual frequency of whatever field the shield consist of is unknown. It's also entirely possible the numeric strings displayed in the bottom part of the image constitute the secret key to a pseudorandom binary sequence that is overlaid onto the useful shield signal, and that's what the Klingon actually use to penetrate them.
- Palomides 3y agoI'm curious about the use cases for 275 ghz wireless communication, are microwave links still common? it's almost far infrared
- woah 3y agoMicrowave links are very common
- wrs 3y agoWiFi is microwaves.
- ianburrell 3y agoThe same use as optical wireless like LiFi. Higher speed over short distances. Optical has the advantage to bouncing off walls, but EHF may have bandwidth advantages. This wouldn't be useful for microwave links since it is absorbed by the atmosphere and has short range. 275 GHz is one the edge of EHF. Terahertz is 300 GHz to 3 THz. Above that is infrared.
- aidenn0 3y ago> This wouldn't be useful for microwave links since it is absorbed by the atmosphere and has short range. Nit-pick; 275GHz isn't terrible for atmospheric absorption. What gets you is the phase dispersion when the humidity is high.
- _fizz_buzz_ 3y agoBy far most communication is in the microwave bands, such as WiFi, cell phones, Bluetooth
- Palomides 3y agosure, but wifi doesn't go over 6ghz for plenty of reasons edit: forgot about 60ghz wifi
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- JohnnyD10 3y agoWhen incorporated into Wifi 18 in the year 2046, it will prove to realistically get around 500 MB/s, and have a hard time getting through most walls.
- I_Am_Nous 3y agoThey are only transmitting 30 mm, when they moved to transmitting 20 meters it had to drop from 64QAM to 32QAM and lost some throughput. It's also laser generated so I don't believe it's omnidirectional, just point to point.
- connicpu 3y agoSounds more practical for satellite-to-satellite communication than for consumer devices then if it's being sent with lasers
- Cthulhu_ 3y agoMight work well in open office and large public spaces though, there's quite a lot of things in between consumer and space.
- aidenn0 3y agoThe transmitted signal is diode generated, not laser-generated, and it's coupled with a typical EHF horn antenna.
- derefr 3y agoIIRC there are modern enterprise wi-fi APs that sit in the rafters, and form star-topology laser relays between devices.
- NavinF 3y agoJokes aside, I get a consistent 1600mbps over wifi 6E which is good enough for me. Of course you need an AP in every room to get consistent performance, but wifi has always been like that. And unless your applications use forward error correction wifi will always have latency spikes from L2 retransmission if there's even one wall between the AP and device
- aDfbrtVt 3y agoSomething not totally clear from the title, but it seems the claimed rate was actually achieve with a transmitter structure similar to what you would find in coherent optics (see figure 4). Instead of coupling to fiber, they couple to a high speed photodiode that radiates at the ~140GHz laser wavelength. EDIT: Noticed that after a closer reading of the paper, the real goal was to assess the LO phase noise improvement when moving from a RF synthesizer to a SBS laser and PD based LO.
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- genman 3y agoDoes 20-m here stand for 20 meters or something else? "We also demonstrate successful 20-m transmission at a data rate of over-200 Gbit/s data rate."
- I_Am_Nous 3y agoYes, it's referring to transmitting with 20 meters between transmitter/receiver. Their highest speed transfer was done at 30 centimeters between transmitter/receiver.
- Animats 3y ago275 GHz. Getting close to terahertz. Nice.
- londons_explore 3y agoThey make a big point of using HD-FEC rather than SD-FEC. To me, that makes no sense - the extra power usage of SD-FEC can be tiny, even at high data rates. The FEC problem can be parallelized (if the protocol is designed for this) so it doesn't need to run at line rate too. (SD-FEC lets you get substantially more data throughput in a given channel).
- aDfbrtVt 3y agoI can think of a number of cases where using a hard decision decoder can be a better choice. Power would be one factor and I would strongly disagree that the power delta between soft and hard codes at these data rates is small. Unfortunately, I can not find any public data to back up that claim for what appear (based on coding gain and overhead) an HD-FEC using RS and a SD-FEC using braided BCH or LDPC. Other factors can include reduced routing complexity and area requirements of HD since you have to shuffle around soft information. Extra die space is expensive so you want to avoid it if possible. However, I think the most likely is the latency reduction you get when using HD-FEC. I know that some applications of microwave links are extremely latency sensitive, could be that this research is targeting one of those applications.
- lacoolj 3y agoWould like to see the environmental impact and public health studies done with this
- NavinF 3y agoPoe's law at work? There are people who unironically want to hold back faster wifi and wait for environmental impact studies
- mikewarot 3y agoWhile it looks like they got lower phase noise using the optical LO than the traditional source, there are better conventional sources, like the LNS Series from NoiseXT. I applaud their novel optical based system of generating the RF to then transmit via the antenna. The world is getting quite interesting, where you can actually buy test equipment these days that will tell you the frequency (down to the Hertz!) of Blue Laser Light.
- Havoc 3y agoGuessing that needs line of sight & stable environment?